Introduce VIR_CONNECT_BASELINE_CPU_IGNORE_HOST flag

Introduce VIR_CONNECT_BASELINE_CPU_IGNORE_HOST flag

With this new flag virConnectHypervisorBaselineCPU can be used on any
host (rather than being limited to hosts described by individual CPUs
passed to the API). Using the flag makes the API behave similarly to the
old virConnectBaselineCPU. The main difference is the CPU definition
accepted by both APIs: the old one only accepts host CPU definition,
i.e., without 'policy' attributes as seen in the host capabilities XML.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>